First‐Principles Study on Lattice Structures and Electronic Properties of Li ₁₀ SnP ₂ S ₁₂ /Li ₂ S Interface

Utilizing density functional theory, this study employed first‐principles calculations to thoroughly examine the interfacial architecture and electrical properties between Li 10 SnP 2 S 12 , a solid electrolyte, and Li 2 S, the cathode material, in all‐solid‐state lithium‐sulfur batteries. The interface between Li 10 SnP 2 S 12 and Li 2 S demonstrates a high degree of structural coherence, with a lattice mismatch of only 3.31%. At an interfacial separation of 1.800 Å, the calculated binding energy at this interface is −3.48 J m −2 . Through the examination of the lattice structures, it can be clearly seen that the formation of the interface expands the transport path of lithium ions on the ab plane, thereby enhancing the cotransport capacity of lithium ions on the LSPS side. At the interface, the overlap of electron orbitals facilitates stronger interfacial bonding, which in turn promotes more efficient ion transport. The density of states at the interface significantly enhances the conductivity and ion conversion efficiency of the battery during operation. The analysis of the density charge difference and Bader charge at the interface reveals a substantial charge transfer in this region. Calculations of the exchange energy show that the interface effectively inhibits sulfur penetration, thereby preserving chemical stability. By analyzing the diffusion behavior of Li ions, it is found that the formation of the interface is beneficial to the transport of lithium ions in Li 2 S, and at the same time, it can enhance the activity of Li 2 S, which brings a positive effect to the operation of lithium‐sulfur batteries.